4.5. GFS2 Quota Management
File-system quotas are used to limit the amount of file system space a user or group can use. A user or group does not have a quota limit until one is set. When a GFS2 file system is mounted with the
quota=on or quota=account option, GFS2 keeps track of the space used by each user and group even when there are no limits in place. GFS2 updates quota information in a transactional way so system crashes do not require quota usages to be reconstructed.
To prevent a performance slowdown, a GFS2 node synchronizes updates to the quota file only periodically. The fuzzy quota accounting can allow users or groups to slightly exceed the set limit. To minimize this, GFS2 dynamically reduces the synchronization period as a hard quota limit is approached.
Note
As of the Red Hat Enterprise Linux 6.1 release, GFS2 supports the standard Linux quota facilities. In order to use this you will need to install the quota RPM. This is the preferred way to administer quotas on GFS2 and should be used for all new deployments of GFS2 using quotas. This section documents GFS2 quota management using these facilities.
For earlier releases of Red Hat Enterprise Linux, GFS2 required the
gfs2_quota command to manage quotas. For information on using the gfs2_quota command, see Appendix A, GFS2 Quota Management with the gfs2_quota Command.
4.5.1. Configuring Disk Quotas
To implement disk quotas, use the following steps:
- Set up quotas in enforcement or accounting mode.
- Initialize the quota database file with current block usage information.
- Assign quota policies. (In accounting mode, these policies are not enforced.)
Each of these steps is discussed in detail in the following sections.
4.5.1.1. Setting Up Quotas in Enforcement or Accounting Mode
In GFS2 file systems, quotas are disabled by default. To enable quotas for a file system, mount the file system with the
quota=on option specified.
It is possible to keep track of disk usage and maintain quota accounting for every user and group without enforcing the limit and warn values. To do this, mount the file system with the
quota=account option specified.
Usage
To mount a file system with quotas enabled, mount the file system with the
quota=on option specified.
mount -o quota=on BlockDevice MountPoint
To mount a file system with quota accounting maintained, even though the quota limits are not enforced, mount the file system with the
quota=account option specified.
mount -o quota=account BlockDevice MountPoint
To mount a file system with quotas disabled, mount the file system with the
quota=off option specified. This is the default setting.
mount -o quota=off BlockDevice MountPointquota={on|off|account}on- Specifies that quotas are enabled when the file system is mounted.off- Specifies that quotas are disabled when the file system is mounted.account- Specifies that user and group usage statistics are maintained by the file system, even though the quota limits are not enforced.BlockDevice- Specifies the block device where the GFS2 file system resides.
MountPoint- Specifies the directory where the GFS2 file system should be mounted.
Examples
In this example, the GFS2 file system on
/dev/vg01/lvol0 is mounted on the /mygfs2 directory with quotas enabled.
mount -o quota=on /dev/vg01/lvol0 /mygfs2
In this example, the GFS2 file system on
/dev/vg01/lvol0 is mounted on the /mygfs2 directory with quota accounting maintained, but not enforced.
mount -o quota=account /dev/vg01/lvol0 /mygfs2
4.5.1.2. Creating the Quota Database Files
After each quota-enabled file system is mounted, the system is capable of working with disk quotas. However, the file system itself is not yet ready to support quotas. The next step is to run the
quotacheck command.
The
quotacheck command examines quota-enabled file systems and builds a table of the current disk usage per file system. The table is then used to update the operating system's copy of disk usage. In addition, the file system's disk quota files are updated.
To create the quota files on the file system, use the
-u and the -g options of the quotacheck command; both of these options must be specified for user and group quotas to be initialized. For example, if quotas are enabled for the /home file system, create the files in the /home directory:
quotacheck -ug /home
4.5.1.3. Assigning Quotas per User
The last step is assigning the disk quotas with the
edquota command. Note that if you have mounted your file system in accounting mode (with the quota=account option specified), the quotas are not enforced.
To configure the quota for a user, as root in a shell prompt, execute the command:
edquota username
Perform this step for each user who needs a quota. For example, if a quota is enabled in
/etc/fstab for the /home partition (/dev/VolGroup00/LogVol02 in the example below) and the command edquota testuser is executed, the following is shown in the editor configured as the default for the system:
Disk quotas for user testuser (uid 501): Filesystem blocks soft hard inodes soft hard /dev/VolGroup00/LogVol02 440436 0 0
Note
The text editor defined by the
EDITOR environment variable is used by edquota. To change the editor, set the EDITOR environment variable in your ~/.bash_profile file to the full path of the editor of your choice.
The first column is the name of the file system that has a quota enabled for it. The second column shows how many blocks the user is currently using. The next two columns are used to set soft and hard block limits for the user on the file system.
The soft block limit defines the maximum amount of disk space that can be used.
The hard block limit is the absolute maximum amount of disk space that a user or group can use. Once this limit is reached, no further disk space can be used.
The GFS2 file system does not maintain quotas for inodes, so these columns do not apply to GFS2 file systems and will be blank.
If any of the values are set to 0, that limit is not set. In the text editor, change the desired limits. For example:
Disk quotas for user testuser (uid 501): Filesystem blocks soft hard inodes soft hard /dev/VolGroup00/LogVol02 440436 500000 550000
To verify that the quota for the user has been set, use the command:
quota testuser
4.5.1.4. Assigning Quotas per Group
Quotas can also be assigned on a per-group basis. Note that if you have mounted your file system in accounting mode (with the
account=on option specified), the quotas are not enforced.
To set a group quota for the
devel group (the group must exist prior to setting the group quota), use the following command:
edquota -g devel
This command displays the existing quota for the group in the text editor:
Disk quotas for group devel (gid 505): Filesystem blocks soft hard inodes soft hard /dev/VolGroup00/LogVol02 440400 0 0
The GFS2 file system does not maintain quotas for inodes, so these columns do not apply to GFS2 file systems and will be blank. Modify the limits, then save the file.
To verify that the group quota has been set, use the following command:
quota -g devel
